Biology Special Lesson: Types of Selection

Overview:
Types of Selection
In this activity you will choose one of the three types of natural selection and create a scenario to illustrate how it affects the traits of a population. You will describe your scenario and reasoning in an essay.

Background Information:
There are three types of natural selection: directional, disruptive, and stabilizing. Each type selects for a different form of a trait within a population.
• Directional selection selects for one extreme of a specific trait. A graph representing the trait within a population would have a peak on the left or right side, but not both. • Disruptive selection selects for BOTH extremes of a specific trait. A graph representing the trait within a population would have two peaks on both the left and right side. • Stabilizing selection selects for the average of a specific trait. A graph representing the trait within a population would peak towards the middle.

Assignment:
In this assignment you will create a scenario that illustrates one of the three types of natural selection. Your scenario must include the type of organism and their population, three variations of a specific trait, and how the population shifted from one version of the trait to another and why. Additionally, you should explain your reasoning as to how this scenario models this type of selection.
Start by choosing one of the three types of selection and an organism to use in your scenario. Identify a specific trait of that organism and three variations of this trait. The variations should represent a spectrum of the trait such as small, medium, large, or light, medium, dark, or smaller amounts, medium amounts, larger amounts. Be creative in developing your scenario and describing the selection of your chosen trait.

Writing Prompt:
Write an essay describing a scenario that illustrates one of the three types of natural selection. Your essay must include the following: a description of the chosen type of selection, an organism and population, three different variations of a specific trait, and how the population shifted from one version of the trait to another and why.